Sentinel IDS Marine Intruder Detection Sonar, Solution to Underwater Threat

by OldSailor on October 27, 2007



This post is to highlight about Sentinel, Intruder Detection Sonar designed to counter the threat of underwater attacks against ships, harbours, coastal industrial installations and offshore oil platforms.

1.System Overview:

A typical Sentinel IDS system comprises:

  • a lightweight sonar head
  • processor platform
  • command workstation and advanced detection
  • tracking and classification software


The Sonardyne Sentinel system has been developed using industry leading techniques, materials and processes. Spares-holding requirements and decreasing future obsolescence issues have been addressed by using COTS based technology.

Sonar Head

The sonar head contains the electronics to control the transmitters and digitize and multiplex the received signals from the transducers. The multiplexed data is transmitted to the topside equipment via a copper-based cable for cable lengths up to 100 metres, or via a fiber optic cable for longer lengths.

The sonar head also contains and attitude and heading reference sensor which monitors the orientation of the head and allows the topside processor to automatically compensate for any motion. This enables the system to be suspended by its own cable from moving platforms such as drifting patrol boats or ships on single point moorings. The head is also small enough to be mounted on an unmanned underwater vehicle.

sentinel_brochure head

Processor and Software

Pulse compression, beam forming and automatic detection and tracking (ADT) are carried out in two high performance PCs installed in a rugged case. The case also contains the power distribution unit for the sonar head.



The command workstation

A third PC, provides a tactical-style display for the system. This shows the sonar data, track data and alerts overlaid on a chart. If multiple sonar heads are deployed, they are all interfaced to the command workstation via an Ethernet LAN, and the tactical display shows all the sonar coverage in the correct geographical locations on the chart.


The Sentinel software

The software has been written using the latest software techniques, allowing full network connectivity. The command workstation supports track export to an external Command and Control system and can be configured for remote Internet access to allow system status reporting from anywhere in the world.

2.Key Features & Benefits:

  • 360 degrees of acoustic coverage
  • Up to 1,800 metre diameter protection zone from a single sonar head
  • Provides robust detection, classification and tracking of targets in a wide range of environments
  • No specialist operator training required
  • Low false alarm rate
  • Autonomous operation from a remote command and control station
  • Up to 10 sonar heads can be networked together for wide area domain awareness
  • Long detection range provides vital time to deploy effective counter measures
  • Reliable discrimination between threats and mammals
  • Third generation sonar ensures optimum performance
  • Man-portable sonar head weighing under 35kg
  • Easily stored for rapid deployment
  • Simultaneous tracking and classification of multiple sonar contacts with low false alarms
  • COTS architecture enables operation on commercial and military assets
  • Cost effective underwater security solution
  • Simple and intuitive software
  • Supported by worldwide Sonardyne network
  • Unattended operation – allows users to assess the status at a glance from across the bridge

3.Operational Scenarios:

Harbour Entrance / Fixed Point Protection


The reliable detection of underwater targets in the acoustic environment of a harbour is a well known problem. Constant vessel traffic, noise from continually active depth sounders and a complex thermal structure typify this scenario.

Sentinel has been specifically designed to cope with these adverse conditions and is capable of tracking thousands of targets in real time with only genuine threats causing an alarm that the operator or observer need react to.

Mounted in a either a seabed frame looking upwards or on a permanent harbour wall mount looking across the entrance, Sentinel is easy to install and configure for autonomous operation from a remote monitoring station.

Networked Port Installation


Under the International Ship and Port Facility Code (ISPS code) it is vital to ensure protection against foreseeable events. Sentinel has been designed to operate in a stand-alone or networked mode with multiple sonar heads to enable complete protection of assets within the security zone.

The commercial off-the-shelf (COTS) based processing units can facilitate up to 10 sonar heads per command station, offering a cost-effective solution to large area coverage. The overlay will increase the level of domain awareness in an estuary, coastal environment or complex port and can be totally integrated into a central command system with above water surveillance.

Sentinel’s unique detection, classification and tracking software has been proven to operate in the harshest environmental conditions including ‘brown’ water, noisy, shallow, tidal harbours where vessel activity results in a lot of disturbance in the water column.

Asset Protection


Sentinel’s compact size and lightweight design make it a practical solution for rapid mobilization to meet an evolving threat. With minimum storage requirements, the Sentinel system can be carried on board as part of a mobile or expeditionary security unit, providing a secure underwater perimeter for high value assets.

With the sonar head weighing under 30kg it can be deployed over the side of the vessel or from a jetty by one person using only minimal equipment. Sonar processor and command workstation set-up is an equally simple task with the full system typically configured and online in under 30 minutes.

Providing wide area coverage, Sentinel is designed to provide secure underwater perimeters for both military and civilian assets. These include: naval vessels at anchor in overseas ports, cruise liners in harbour and super yachts moored off the coast.

Energy Infrastructure


The threat of insurgency, vandalism or criminal activity is not restricted to ports or military assets. Any oil and gas installation, whether coastal or offshore, is extremely vulnerable to attack from below and represents a significant threat to a region’s energy supplies Sentinel’s open system architecture allows integration of the sub-sea security zone with conventional terrestrial security systems, including thermal imaging, radar and ground sensing devices.

The Sentinel system has been developed from the outset with flexible deployment in mind. It can be mounted from a pole based deployment system, suspended from its combined signal and power cable or mounted on the seabed. Considerations such as ease of installation by divers in low visibility have been taken into consideration in the Sentinel system from the very beginning. Sonardyne has a proven track record in deployment systems and can recommend the most appropriate solution.

Watch the animated video of IDS in Action (3:50 minutes)

Download animated video click here.

OldSailors view: Very useful for countries having assets in coastal area, to protect against any underwater intruders/threats.

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